Early cell-autonomous and niche-mediated epithelial response to influenza infection in primary alveolar organoids.

Summary

Using murine and human primary alveolar organoids with paired single-nucleus RNA/ATAC sequencing, the study establishes robust methods to model early IAV infection and delineates conserved AT2 injury programs. Notably, uninfected AT2 cells rapidly acquire damage-associated states driven by the inflammatory niche, defining a conserved epithelial response signature with implications for ARDS pathogenesis.

Key Findings

• Established robust IAV infection protocols in primary murine and human alveolar organoids.
• Infected AT2 cells showed early surfactant secretion loss, decreased lipid biogenesis, a rapid antiviral response burst, and later viral-mediated suppression.
• Uninfected AT2 cells underwent rapid transcriptional/epigenomic reprogramming to damage-associated states driven by the inflammatory milieu.
• Defined a conserved AT2 response signature to IAV with implications for ARDS pathogenesis.

Clinical Implications

Identifying early AT2 dysfunction (surfactant loss, lipid biogenesis decline) and inflammatory niche-driven bystander injury suggests targets for early intervention (e.g., preserving surfactant biology, modulating paracrine inflammatory cues) and potential biomarker development.

Limitations

• In vitro organoid systems may not fully recapitulate immune-vascular interactions present in vivo.
• Focus on IAV limits extrapolation to other respiratory viruses and bacterial pneumonias.

Future Directions

Validate the AT2 response signature in patient biospecimens (e.g., BAL, autopsy), map the paracrine mediators driving bystander injury, and test interventions that preserve surfactant/lipid programs during early infection.